Barr Pharmaceuticals says that US regulators have given the green light to its generic version of Bayer’s blockbuster oral contraceptive Yasmin.

The US Food and Drug Administration has approved the firm’s Abbreviated New Drug Application to manufacture and market a generic version of Yasmin (drospirenone and ethinyl estradiol). The decision comes after a US district court found in March that the patent held by Bayer was invalid because it was obvious. The Leverkusen-based drugmaker has appealed the ruling.

Barr said it expects to start selling its version of Yasmin in the middle of this year and the ‘first-to-file’ approval will give it 180 days of exclusivity. Yasmin had branded annual sales of about $575 million by the end of February, the US firm noted.

The Yasmin news came just after Barr has posted a disappointing set of quarterly results which led to its shares sliding 23%. Net income rose to $23 million, or $0.21 per share, from $11.6 million, or $0.11 per share, and revenues rose 2% to $608 million. However US generic sales fell 15% to $261 million.

Barr cut its full-year earnings per share forecast to $2.75-$3.05, down from an estimate in February of $3.05-$3.35. Chief executive Bruce Downey said that the results did not meet expectations but will improve in the second half of the year “and demonstrate the value of expanding our operations and markets outside the USA."